JP7073957B2 - Lens drive device - Google Patents

Description

The present invention relates to a lens driving device.

As a lens driving device used in an image pickup device mounted on a mobile phone or the like, Patent Document 1 below discloses a lens driving device that moves a lens frame in which a lens is fitted by a piezoelectric actuator in the optical axis direction. In the lens driving device of Patent Document 1, a leaf spring member arranged along the outer periphery of the lens frame body urges a piezoelectric actuator arranged on the outer periphery of the lens frame body toward the lens frame body to cause a lens. The frame is frictionally engaged with the piezoelectric actuator.

Japanese Patent No. 6024798

The image pickup device in which the above-mentioned lens driving device is used is required to have impact resistance to the extent that it can withstand an impact when dropped, and the lens driving device is also required to have high impact resistance.

After diligent research, the inventors have discovered a new technique that can improve the impact resistance of the lens drive device.

An object of the present invention is to provide a lens driving device having improved impact resistance.

The lens driving device according to one aspect of the present invention is located above the lower support member and the lower support member, and is overlapped and adhered to the lens frame to which the lens is attached and the upper side of the lower support member. An upper support member that accommodates the lens frame between the lower support member and an outer peripheral portion of the lens frame that extends along the optical axis direction of the lens and can be expanded and contracted in the optical axis direction of the lens. Is adhered to the upper support member and the lower end portion is adhered to the lower support member, and the lower end portion extends along the outer periphery of the lens frame body so as to urge the upper end portion of the actuator toward the lens frame body side. It includes a leaf spring member having a first end portion that is frictionally engaged with the outer periphery of the upper end portion and a second end portion that is attached to the lens frame.

In the actuator of the lens driving device, the upper end portion is adhered to the upper support member and the lower end portion is adhered to the lower support member. Therefore, the position and orientation of the actuator are held with high accuracy by the upper support member and the lower support member. Therefore, in the above-mentioned lens driving device, the situation where the actuator is damaged even when an impact is applied is suppressed, and high impact resistance can be realized.

In the lens driving device according to the other aspect of the present invention, the upper support member has an opening into which the upper end of the actuator enters, and the actuator supports the upper end on the outer periphery of the upper end into the opening of the upper support member. It is adhered to the member.

In the lens driving device according to the other aspect of the present invention, the lower support member has an opening into which the lower end of the actuator enters, and the actuator is placed on the outer periphery of the lower end into the opening of the lower support member. It is adhered to the lower support member.

In the lens driving device according to the other aspect of the present invention, the lower support member has a rectangular shape when viewed from the optical axis direction of the lens, and has a side wall portion bonded to the upper support member at one corner. The actuator is arranged in the corner where the side wall is provided.

In the lens driving device according to the other aspect of the present invention, the actuator extends along the expansion / contraction direction and is joined to the piezoelectric element having the upper end and the lower end and the upper end of the piezoelectric element, and the leaf spring member rubs around the outer periphery. It has a drive shaft to be engaged, and the lower end of the piezoelectric element is fixed to the lower support member.

According to various aspects of the present invention, a lens driving device with improved impact resistance is provided.

It is an exploded perspective view which showed the lens drive device which concerns on one Embodiment. It is a perspective view which showed the lens driving part of FIG. It is a perspective view which showed the lens drive part in the state which removed the cap. It is a top view of the lens drive part shown in FIG. It is a side view which showed the actuator and the friction engagement member. It is sectional drawing around an actuator. It is a top view of the drive main body part of FIG. It is sectional drawing at the bonding point of the weight part of a piezoelectric actuator and a base member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same code will be used for the same element or the element having the same function, and duplicate description will be omitted.

As shown in FIG. 1, the lens driving device 1 includes a lens driving unit 2 and a cover 3 that covers the lens driving unit 2, and has a lens optical axis L that is an optical axis of the lens 4 to be attached. The lens 4 may be a single lens or a lens barrel including a plurality of lenses.

As shown in FIG. 2, the lens drive unit 2 has a substantially square columnar outer shape, and includes a cap (upper support member) 10 and a drive body unit 20. The cap 10 and the drive main body 20 are overlapped with each other along the direction of the lens optical axis L. Further, both the cap 10 and the drive main body 20 have through holes 10a and 20b extending along the direction of the lens optical axis L, respectively. In the present embodiment, the lens 4 is screwed into the drive main body 20 so as to be accommodated in the through hole 20a of the drive main body 20. For example, a male screw portion may be formed on the outer peripheral surface of the lens 4, and a female screw may be formed on the inner peripheral surface of the through hole 20a of the drive main body portion 20. The diameter of the through hole 20a of the drive main body 20 is designed to be the same as the diameter of the lens 4, and the through hole 10a of the cap 10 is also designed to be the same as the diameter of the lens 4.

Hereinafter, the configuration of the drive main body 20 will be described in more detail with reference to FIGS. 3 to 5.

As shown in FIG. 3, the drive main body portion 20 includes a base member (lower support member) 30 and a lens frame body 40.

The base member 30 extends in a direction orthogonal to the lens optical axis L. As shown in FIG. 4, the base member 30 exhibits a substantially square shape in a plan view (that is, when viewed from the direction of the lens optical axis L). An opening 31 to which the actuator 54 described later is attached is provided at one corner of the base member 30. In the present embodiment, the opening 31 is an opening for accommodating and fixing the weight portion 57 of the actuator 54. Further, the base member 30 is provided with a side wall portion 32 at a corner portion diagonally related to the corner portion where the opening portion 31 is provided. The side wall portion 32 is provided with a notch portion 33 for accommodating the protruding portion 42 of the lens frame body 40. The base member 30 is made of, for example, a resin material (liquid crystal polymer or the like) containing a filler made of glass, an inorganic material, or the like. The base member 30 can be formed, for example, by injection molding.

The base member 30 is provided with an outer peripheral wall portion 34 around the lens frame body 40. The height of the outer peripheral wall portion 34 is designed to be, for example, about half the height of the lens frame body 40. The outer peripheral wall portion 34 is provided at least in a corner portion where the opening portion 31 is provided. In the present embodiment, the cap 10 stacked on the upper side of the base member 30 is provided with the outer peripheral wall portion 12 corresponding to the outer peripheral wall portion 34 of the base member 30. The height of the outer peripheral wall portion 12 is designed to be, for example, about half the height of the lens frame body 40. The outer peripheral wall portion 12 is provided at least in a region corresponding to the outer peripheral wall portion 34 provided in the corner portion where the opening portion 31 is provided. In the present embodiment, the height of the base member 30 and the height of the cap 10 are designed to be substantially the same, and the outer peripheral wall portions 12a and 34a are also designed to be substantially the same. The outer peripheral wall portion 12 of the cap 10 and the outer peripheral wall portion 34 of the base member 30 are in contact with each other and are bonded by an adhesive.

Like the base member 30, the lens frame 40 extends in a direction orthogonal to the lens optical axis L. The lens frame body 40 is arranged so as to be parallel to the base member 30 on the upper side with respect to the lens optical axis L. The lens frame body 40 has a through hole 40a corresponding to the above-mentioned through hole 20a. As shown in FIG. 4, the lens frame body 40 exhibits a substantially square shape in a plan view, like the base member 30. An actuator 54 is attached to the outer periphery of the lens frame 40 by using a friction engaging member 50 at a portion corresponding to a corner portion where an opening 31 of the base member 30 is provided. The lens frame body 40 has an accommodating portion 43 accommodating a fixed end portion 51b of a leaf spring member 51, which will be described later. The fixed end portion 51b of the leaf spring member 51 is held and fixed in the accommodating portion 43 to form the fulcrum P2 of the leaf spring member 51.

The lens frame body 40 is housed between the cap 10 and the base member 30. The cover 3 shown in FIG. 1 covers the entire lens driving unit 2 configured to accommodate the lens frame 40 between the cap 10 and the base member 30 from above. A slight gap is provided between the inner surface of the cover 3 and the outer peripheral surface of the cap 10 and the base member 30, and the cover 3 and the base member 30 are adhered to each other by the adhesive material supplied to the gap. ing.

The actuator 54 is a piezoelectric actuator provided with a Smooth Impact Drive Mechanism. As shown in FIG. 5, the actuator 54 comprises a prismatic piezoelectric element 55, a drive shaft 56 joined to the top surface 55a of the piezoelectric element 55, and a weight portion 57 joined to the bottom surface 55b of the piezoelectric element 55. include. An adhesive such as an epoxy adhesive can be used for joining the piezoelectric element 55 to the drive shaft 56 and the weight portion 57.

The piezoelectric element 55 is made of a piezoelectric material, and the piezoelectric material includes lead zirconate titanate (so-called PZT), crystal, lithium niobate (LiNbO ₃ ), and potassium tantalate niobate (K (Ta, Nb). ) O ₃ ), barium titanate (BaTIO ₃ ), lithium tantalate (LiTaO ₃ ) and strontium titanate (SrTiO ₃ ) and other inorganic piezoelectric materials can be used. The piezoelectric element 55 can have a laminated structure in which a plurality of piezoelectric layers made of the above-mentioned piezoelectric material and a plurality of electrode layers are alternately laminated. A pair of electrodes (not shown) connected to the electrode layer are provided on the side surface of the piezoelectric element 55, and by applying a voltage to the piezoelectric element 55 by the pair of electrodes, the axis (Z in FIG. 5) is provided. It is adjusted to extend or contract in the direction of the axis) (polarization of piezoelectric ceramics, etc.). Therefore, the expansion and contraction of the piezoelectric element 55 can be controlled by controlling the voltage applied between the pair of electrodes. The piezoelectric element 55 is not limited to a prismatic shape as long as it has a shape that can be expanded and contracted in one direction, and may be a cylindrical shape or the like.

The drive shaft 56 is made of a composite resin material containing fibers such as carbon fiber. The drive shaft 56 has a columnar shape wider than that of the piezoelectric element 55, and is aligned with the Z axis of the piezoelectric element 55.

The weight portion 57 is made of a material having a high specific density such as tungsten or a tungsten alloy, and is designed to be heavier than the drive shaft 56. By making the weight portion 57 heavier than the drive shaft 56, the weight portion 57 is less likely to be displaced when the piezoelectric element 55 expands and contracts, and the drive shaft 56 can be displaced more efficiently. The weight portion 57 has a rectangular flat plate shape and is aligned with the Z axis of the piezoelectric element 55. In the actuator 54, the weight portion 57 is housed in the opening portion 31 of the base member 30 and is fixed. At this time, the axis Z of the piezoelectric element 55 of the actuator 54 is designed to be parallel to the lens optical axis L. The weight portion 57 of the actuator 54 and the opening portion 31 of the base member 30 can be fixed by adhesion.

The friction engagement member 50 that is frictionally engaged with the actuator 54 includes a leaf spring member 51 and a slider 52.

The leaf spring member 51 is an elastic strip-shaped member (for example, a strip-shaped member made of stainless steel), and is arranged on the outer periphery of the lens frame 40. The leaf spring member 51 is made of an alloy plate material or a metal plate material, and can be obtained by punching or bending a single plate material. The leaf spring member 51 is composed of one member, and a plurality of members are not joined by welding or the like. Further, the leaf spring member 51 is not branched when viewed from the direction of the lens optical axis L or the direction orthogonal to the lens optical axis L (that is, the side surface direction).

As shown in FIG. 5, when viewed from the side surface direction, the leaf spring member 51 extends along the outer periphery of the lens frame body 40 and is substantially orthogonal to the lens optical axis L. The leaf spring member 51 has a tip portion 51a (first end portion) and a fixed end portion 51b (second end portion).

The tip portion 51a is a free end of the leaf spring member 51 and is in contact with the drive shaft 56 of the actuator 54. The leaf spring member 51 urges the drive shaft 56 toward the lens frame 40 at the tip portion 51a and is frictionally engaged with the actuator 54. In the tip portion 51a, the portion where the leaf spring member 51 and the drive shaft 56 are in contact with each other is the point of action P1 of the leaf spring member 51. The tip portion 51a extends so as to be orthogonal to the axis Z of the lens optical axis L and the piezoelectric element 55 of the actuator 54, and the tip portion 51a has a uniform width (that is, a length in the lens optical axis L direction). Have.

The fixed end portion 51b is fixed to the lens frame body 40. The fixed end portion 51b extends so as to be orthogonal to the axis Z of the lens optical axis L and the piezoelectric element 55 of the actuator 54, and the fixed end portion 51b has a uniform width. The width of the tip portion 51a is narrower than the width of the fixed end portion 51b. By narrowing the tip portion 51a in this way, the movable range of the tip portion 51a that moves the drive shaft 56 in the Z-axis direction is widened. As a result, the driveable distance (stroke) of the leaf spring member 51 and the lens frame body 40 can be extended.

A connecting portion 51c is interposed between the tip portion 51a and the fixed end portion 51b, and the tip portion 51a and the fixed end portion 51b are connected by the connecting portion 51c. The width of the connecting portion 51c is not uniform, and the width gradually narrows from the fixed end portion 51b toward the tip portion 51a. The height position (position related to the lens optical axis L) of the leaf spring member 51 is shifted at the connecting portion 51c, and the height position of the center line of the tip portion 51a is higher than the height position of the center line of the fixed end portion 51b. It's getting higher.

The slider 52 is fixed to a slider fixing portion 41 provided on the outer peripheral surface of the lens frame 40. A right-angled corner is defined on the outer peripheral surface of the slider fixing portion 41, and the slider 52 is a plate-shaped member (for example, a stainless steel plate-shaped member) bent at a right angle along the corner. be.

Then, the portion of the drive shaft 56 of the actuator 54 is sandwiched between the tip portion 51a of the leaf spring member 51 and the slider 52. At this time, since the leaf spring member 51 urges the actuator 54 toward the slider 52, a predetermined frictional force is generated between the friction engaging member 50 and the actuator 54, and the friction engaging member 50 Frictionally engages with the drive shaft 56 of the actuator 54. Further, the lens frame 40 to which the friction engaging member 50 is attached is also frictionally engaged with the drive shaft 56 of the actuator 54 via the friction engaging member 50.

In the lens drive device 1, the friction engagement member 50 frictionally engaged with the outer periphery of the drive shaft 56 of the actuator 54 is a lens frame body by causing a speed difference between expansion and contraction when the actuator 54 is expanded and contracted. Together with 40, it is driven in the expansion / contraction direction (that is, the Z-axis direction) of the actuator 54.

As shown in FIG. 4, the lens drive unit 2 has a region corresponding to a corner portion of the base member 30 provided with an opening portion 31 and a corner portion different from the corner portion provided with the side wall portion 32. A circuit unit 60 is provided. The circuit unit 60 includes a flexible substrate and a position sensor unit. The flexible substrate is provided so as to cover the outer peripheral surface of the lens frame 40 along the two sides sandwiching the corner where the circuit portion 60 is provided. The flexible substrate is formed with, for example, a circuit and wiring for controlling the voltage applied to the actuator 54 described above. The magnetic sensor detects the displacement of the lens frame 40 with respect to the direction of the lens optical axis L by detecting the change in the magnetic flux from the magnet provided on the lens frame 40.

Here, the holding state of the actuator 54 will be described with reference to FIGS. 6 to 8.

The actuator 54 is adhered to the cap 10 at the upper end as shown in FIGS. 6 and 7. Specifically, an opening 13 is provided in the region of the cap 10 corresponding to the actuator 54, and the inner surface of the opening 13 and the outer peripheral surface of the upper end of the drive shaft 56 of the actuator 54 are adhered to each other. .. As shown in FIG. 7, the opening 13 has a U-shape in which the lens optical axis L side is cut out in a plan view (that is, when viewed from the direction of the lens optical axis L). More specifically, the opening 13 exhibits an arc shape centered on the Z axis (a superior arc having a central angle larger than 180 degrees) in a plan view. When the opening 13 is made into a perfect circle centered on the Z axis, a thin and structurally fragile portion is formed on the L side of the lens optical axis, so that the opening 13 is U-shaped rather than a perfect circle. The shape is preferable. In this embodiment, the radius of the arc of the opening 13 is designed to be slightly larger than the radius of the drive shaft 56. An adhesive A1 is supplied between the outer peripheral surface of the drive shaft 56 and the inner surface of the opening 13, and the drive shaft 56 and the cap 10 are adhered to each other by the adhesive A1. The adhesive material A1 has a U-shape in a plan view like the opening 13.

Further, as shown in FIGS. 6 and 8, the actuator 54 is adhered to the base member 30 at the lower end portion. Specifically, an opening 31 is provided at the position of the actuator 54 of the base member 30, and the inner surface of the opening 31 and the outer peripheral surface of the weight portion 57 of the actuator 54 are adhered to each other. As shown in FIG. 8, the opening 31 has a substantially rectangular shape in a plan view (that is, when viewed from the direction of the lens optical axis L). In this embodiment, the size of the opening 31 is designed to be slightly larger than the size of the weight portion 57. An adhesive A2 is supplied between the outer peripheral surface of the weight portion 57 and the inner side surface of the opening 31, and the weight portion 57 and the base member 30 are adhered to each other by the adhesive material A2. Like the opening 31, the adhesive A2 has a rectangular shape in a plan view. The type of the material constituting the adhesive material A2 may be the same as the type of the material constituting the adhesive material A2 described above.

In the lens drive device 1 described above, the upper end portion of the drive shaft 56 of the actuator 54 is adhered to the cap 10, and the weight portion 57 is adhered to the base member 30. Therefore, the position and orientation of the actuator 54 are held with high accuracy by the cap 10 and the base member 30. Therefore, the lens driving device 1 can suppress the situation where the actuator 54 is damaged even when an impact is applied, and has high impact resistance.

Further, in the lens driving device 1, the cap 10 has an opening 13 into which the upper end portion of the actuator 54 enters, and the actuator 54 adheres to the cap 10 on the outer periphery of the upper end portion entering the opening 13 of the cap 10. Has been done. By inserting the upper end portion of the actuator 54 into the opening 13 of the cap 10, the height position of the lower surface of the cap 10 is set to the height position of the upper end surface of the actuator 54 without the cap 10 coming into contact with the upper end portion of the actuator 54. Can be lower. That is, by lowering the height of the cap 10, the height of the lens driving device 1 is reduced.

Further, in the lens driving device 1, the base member 30 has an opening 31 into which the lower end portion of the actuator 54 enters, and the actuator 54 has a base member on the outer periphery of the lower end portion entering the opening 31 of the base member 30. It is adhered to 30. By inserting the lower end portion of the actuator 54 into the opening portion 31 of the base member 30, the actuator 54 moves downward as a whole, so that the lens drive device 1 is further reduced in height.

Moreover, in the lens driving device 1, a part of the outer peripheral wall portion 34 of the base member 30 is located at the same corner as the actuator 54 when viewed from the direction of the lens optical axis L. That is, the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 are in contact with each other in the vicinity of the actuator 54 and adhered to each other. The portion where the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 come into contact with each other functions as a support column for reinforcing the actuator 54, and suppresses a situation in which the actuator 54 is tilted so as to deviate from the lens optical axis L. be able to. The portion where the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 abut is the lens optical axis L when viewed from the direction of the lens optical axis L from the viewpoint of not hindering the movement of the lens frame body 40. It is preferable that the location is far from the actuator 54.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the drive shaft and the weight portion of the piezoelectric actuator can be omitted as appropriate, and the piezoelectric actuator may be composed of only the piezoelectric element. Further, the actuator is not limited to the above-mentioned piezoelectric actuator, and may be an electromagnetic drive type actuator including a magnet and a coil, or a drive type actuator using a shape memory alloy.

1 ... lens drive device, 10 ... cap, 12 ... outer peripheral wall, 13 ... opening, 20 ... drive body, 30 ... base member, 31 ... opening, 34 ... outer wall, 40 ... lens frame, 50 ... Friction engagement member, 51 ... Leaf spring member, 51a ... Tip, 51b ... Fixed end, 51c ... Connection, 54 ... Actuator, 55 ... Piezoelectric element, 56 ... Drive shaft, 57 ... Weight, L ... Lens optical axis.

Claims (6)

With the lower support member,
A lens frame body located above the lower support member and to which a lens is attached,
An upper support member that is overlapped and adhered to the upper side of the lower support member and accommodates the lens frame between the lower support member and the lower support member.
It extends along the optical axis direction of the lens on the outer periphery of the lens frame, can expand and contract in the optical axis direction of the lens, the upper end portion is adhered to the upper support member, and the lower end portion is the lower side. The actuator bonded to the support member and
A first end that extends along the outer circumference of the lens frame and is frictionally engaged with the outer circumference of the upper end so as to urge the upper end of the actuator toward the lens frame, and the lens frame. With a leaf spring member having a second end attached to the body ,
The actuator includes a weight portion, and the lower end portion is configured by the weight portion.
The lower support member has an opening into which the weight portion of the actuator enters.
The actuator is a lens driving device that is adhered to the lower support member on the outer periphery of the weight portion that has entered the opening of the lower support member . The upper support member has an opening into which the upper end of the actuator enters.
The lens driving device according to claim 1, wherein the actuator is adhered to the upper support member on the outer periphery of the upper end portion that has entered the opening of the upper support member. The lower support member has a rectangular shape when viewed from the optical axis direction of the lens, and has a side wall portion to be adhered to the upper support member at one corner.
The lens driving device according to claim 1 or 2 , wherein the actuator is arranged in a corner portion where the side wall portion is provided. The actuator has a piezoelectric element that extends along the expansion and contraction direction and has an upper end and a lower end, and a drive shaft that is joined to the upper end of the piezoelectric element and the leaf spring member is frictionally engaged with the outer periphery. death,
The lens driving device according to any one of claims 1 to 3 , wherein the weight portion is joined to the lower end of the piezoelectric element. Further equipped with a lens attached to the lens frame,
The lens driving device according to any one of claims 1 to 4, which does not have a lens other than the lens attached to the lens frame between the upper support member and the lower support member. The bonding points between the upper support member and the lower support member are the bonding points between the upper end portion of the actuator and the upper support member, the lower end portion of the actuator, and the lower support portion in the optical axis direction of the lens. The lens driving device according to any one of claims 1 to 5, which is located between the parts to be bonded to the member.

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